PROJECT SUMMARY ! Sound transmission to the sensory cells of the inner ear is affected by a variety of passive macro-mechanical influences related to the outer ear, middle ear, and the surrounding bony structure of the inner ear. Abnormal macro-mechanics in otologic pathologies such as otosclerosis, ossicular discontinuity and superior canal dehiscence (SCD) can result in common debilitating auditory and vestibular symptoms such as hearing loss, blocked sensation of the ear, and vertigo induced by noise and pressure. The mechanisms by which many mechanical pathologies cause such symptoms are not well understood, and these pathologies are challenging to diagnose and treat. The purpose of this project is to improve our knowledge of the mechano-acoustic mechanisms in the normal and abnormal ear, enabling us to develop advanced diagnostic methods. In this proposal, we will focus on improving wideband acoustic immittance, a mechano-acoustic measurement taken at the ear canal that measures how much sound is reflected by the eardrum. WAI is a non-invasive, inexpensive approach with the potential to differentiate among middle ear and inner ear lesions that can present with similar symptoms. A non-invasive diagnostic method to detect various macro-mechanical pathologies would be an important development, preventing unnecessary surgery and improving patient outcomes. In Aim 1, we propose to use simple lumped element models and computational statistics to simulate and classify clinical WAI data from patients with otosclerosis, ossicular discontinuity and superior canal dehiscence (SCD), and explore the use of finite element modeling techniques to study the mechanisms of how specific pathologies contribute to changes in WAI. In Aim 2, we will evaluate the utility of WAI in monitoring short- and long-term postoperative mechanical changes after SCD surgery. We aim to help the millions of patients requiring solutions to common conductive pathologies through improvements in diagnosis prior to surgery and monitoring of mechanical changes postoperatively using non-invasive diagnostic methods. !